The LLVM logo is a stylized wyvern (a kind of
dragon). Dragons have
connotations of power, speed and intelligence, and can also be sleek, elegant,
and modular (err, maybe not). In addition, there is a series of influential
compiler
books going back to 1977 which featured dragons on the cover.

Here is the image in a couple of sizes:

Derivative Versions

Here are several derivative versions of the dragon logo, which may be more
suitable for use as icons etc. These were contributed by Teresa Chang:

Usage Rights

This dragon image is owned by Apple Inc. and is available for your
download and use royalty-free. By downloading this image, Apple grants you,
and you accept, a non-exclusive license to use this image. All right, title
and interest in the image, including the copyright therein, is retained by
Apple.